In order to convey a large number of persons by way of an elevator installation within a short time, it is known from the international laid-open specification WO 2004/048243 A1 for at least two elevator cars to be arranged in one shaft, and for said elevator cars to travel vertically upward and downward along a common traveling path separately from one another. Each elevator car is assigned a travel drive, which can impart the traveling movement of the elevator car.
To achieve a high level of transport capacity, it is advantageous if a passenger outside the shaft can, by way of a control device of the elevator installation, input a destination call indicating his or her travel destination. The control device can then perform an allocation assessment for each of the elevator cars and can assign the destination call to the elevator car with the best allocation assessment.
The elevator cars normally have an intentional safety spacing which ensures that, when two elevator cars are traveling one behind the other, the elevator car at the rear in the direction of travel can be reliably braked without the risk of a collision even if the elevator car at the front in the direction of travel brakes abruptly in the event of a fault.
Elevator installations are also known in which two elevator cars arranged one above the other are permanently connected to one another and simultaneously call at two mutually directly adjacent floors. The two elevator cars are driven by a common travel drive and form a so-called double-decker elevator.
To be able to adapt the spacing of the two elevator cars of a double-decker elevator to different spacings between floors, double-decker elevators of cumbersome construction are known in which the two elevator cars are held movably in a common frame and can be offset relative to one another in a vertical direction by way of an additional drive unit, such that the vertical spacing between the elevator cars can be adapted to the spacings between adjacent floors.
Double-decker elevators are suitable in particular for shuttle transport between two directly adjacent starting floors and two fixedly predefined, mutually directly adjacent destination floors. Double-decker elevators exhibit only limited suitability for travel between individually selectable starting and destination floors, because the imperative need for the two elevator cars to stop at mutually directly adjacent floors restricts the transport capacity.
Accordingly, there is a need for an elevator installation of the type discussed above that has a simple construction and permits the elevator cars to travel with large and small spacings between one another without the risk of collision.